The chemical structure of voriconazole (CAS No.:137234-62-9) had been disclosed in European patent EP 0440372A1, as following:

The product was approved by the US FDA in May, 2002, its brand name as Vfend or WEIFAN (in PINYIN). Voriconazole is a second-generation synthetic triazole antifungal agent, its mechanism of action is to inhibit the demethylation of 14 α-lanosterol mediated by cytochrome P-450 in fungi, thereby to inhibit the biosynthesis of ergosterol. The studies in vitro has shown that voriconazole has a broad spectrum of antifungal action. The drug has been shown to be active against Candida species (including strains of Candida krusei, Candida glabrata, and Candida albicans resistant to fluconazole), and has been shown to be active against all tested Aspergillus fungi. Furthermore, voriconazole exhibits in vitro activity against other pathogenic fungi, including those with reduced susceptibility to current available antifungal agents, such as Scedosporium and Fusarium species. In conclusion, voriconazole has a broad spectrum and more potency of antifungal virtue, particularly good efficacy in the treatment of infiltrating infection by invasive Aspergillus. The approved dosage forms of voriconazole include: lyophilized powder for injection, tablets, dry suspension, which could be orally or i.v. administrated, wherein intravenous administration is mainly applied in ICU (intensive care unit) during or after the operation of oncology, hematology, department of burns, and general surgery. Because solubility of voriconazole in water is very little (almost insoluble at pH=7, and 0.2mg/m1 at pH=3), it is unstable in water, and susceptible to be hydrolysized into its enantiomeric configuration (2S,3R). Therefore, an intravenous aqueous formulations with enough shelf life would be developed until the key issue of its solubility has been settled. These problems becomes more serious to semi-polar compound of voriconazole (logD=1.8), because there are no conventional way, such as adding oil and surfactants and the like, could dissolve voriconazole.
The European patent EP 0440372A1 taught to formulate voriconazole with cyclodextrin, however, so far it is generally suspected that the underived or unmetabolized cyclodextrin may cause toxic adverse effect to human body, and be unsuitable to be a pharmaceutical excipient.
In the lyophilized formulation of voriconazole for injection marketed by Pfizer Co., the solubility of voriconazole was increased by using a kind of solubilizer, sulfobutyl ether β-cyclodextrin sodium (SBECD). The amount of SBECD in 1 milligram of lyophilized formulation of approved voriconazole (labeled amount) is about 15 mg˜18 mg (1:15), therefore a large amount of sulfobutyl ether β-cyclodextrin sodium was used in the lyophilized formulation, and encapsuled voriconazole to increase its solubility. This method substantially resolve the problem of water solubility of voriconazole. However, with the deeper investigations on β-cyclodextrin serial derivatives, it was worried about the safety of clinically application of sulfobutyl ether β-cyclodextrin sodium. More and more studies in pharmacology and toxicology had demonstrated that β-cyclodextrin derivatives including sulfobutyl ether β-cyclodextrin sodium would be highly risky to human body. The toxicological studies on repeated administration of sulfobutyl ether β-cyclodextrin sodium had shown that SBECD primarily effected the vacuale formation in the urinary-tract epithelium, as well as activated macrophages in liver and lung. The positive result had been obtained from guinea pig maximization test (GPMT), which indicated that the intravenous formulation had the possibility of causing the allergy. In the two-year animal teratogenicity and carcinogenecity experiments, there were evidences to demonstrate that it was carcinogenic (pancreatic carcinoma) in rodent, and the results of studies also indicated its possibility of carcinogenesis in human. The primary disadvantages of sulfobutyl ether β-cyclodextrin sodium existed in the renal toxicity and hemolysis. Metabolism of this excipient in vivo mainly depended on the renal metabolism. Particularly hydroxypropyl-β-cyclodextrin, an impurity incorporated by the excipient itself, which was more renal toxic, as well as voriconazole itself, therefor the combination of these two components in the lyophilized formulation for intravenous administration clinically restricted to those patients with renal insufficiency and should be strictly used with caution! The results in hemolytic studies of sulfobutyl ether β-cyclodextrin sodium had shown that mild hemolysis could occur at 0.02 mg/ml in the route of intravenous administration, and significant heamolysis at 0.04 mg/ml. The results in long-term toxicity studies of sulfobutyl ether β-cyclodextrin sodium demonstrated that the course of treatment shouldn't be beyond 6 months with lyophilized pharmaceutical formulation for intravenous administration comprising voriconazole and sulfobutyl ether β-cyclodextrin sodium. Because the excipient had the above disadvantage, European Pharmaceutical Affairs Committee, US FDA and Chinese SFDA have required to scientifically re-evaluate the safety of this kind of pharmaceutical excipients. Because The solubility of voriconazole increased by sulfobutyl ether β-cyclodextrin sodium may cause the issues of its safety when applied clinically, it is important that a more scientific and safe voriconazole formulation for injection should be developed.
Pharmaceutical Plant of Zhuhai Livzon Group in China had used a special organic solvent, which is an admixture of certain ratio (2:3) of propylene glycol and ethanol, to dissolve the sterile powder of voriconazole, subsequently dissolved in the transfusion to be infused, in order to resolve the problem of voriconazole's solubility. Although propylene glycol and ethanol are safe when clinically used at a lower dose, there are also obvious disadvantages when this solvent solubilization method is clinically applied: firstly, special organic solvent to dissolve voriconazole (because 100 mg of sterile powder requires to be dissolved in 5 ml (2:3) of propylene glycol and ethanol, and the dosage for an adult is generally 400 mg of voriconazole, which requires to be dissolved in 20 ml (2:3) of propylene glycol and ethanol) in blood stream is mainly metabolized by liver and kidney, as a result, the organic solvent in blood aggravates the metabolic load of patient's liver and kidney. Secondly, the special organic solvents greatly interfere the detection of bacterial endotoxin, as a result the detection and quality controlling become difficult. Thirdly, the improvement for the solubility of voriconazole by these special organic solvents is still quite limited, when 400 mg of voriconazole is generally administrated to an adult, which requires to use 20 ml of propylene glycol and ethanol to dissolve, and then 500 ml infusion at least is required to dilute for transfusion, if 250 ml of infusion is used to dilute, the crystal may be precipitated, resulting in high risk in the safety. Although 500 ml of infusion has been used for dilution, the stability of the resulting solution is still greatly effected by the temperature of environment. In conclusion, it is very inconvenient in clinical application, and difficult to be extended.
In addition, it has shown that there is a disadvantage in the stability of product, because the inactive enantiomer of voriconazole has been detected in the accelerated experiment of the above voriconazole injection marketed.